Fuel injection pump



y 1956 w. E. MEYER 2,746,443

FUEL INJECTION PUMP Filed Feb. 20, 1955 3 Sheets-Sheet 1 IN V EN TOR.WOLFGANG- 4. M5 YEA? BY fiTOENE Y May 22, 1956 w. E. MEYER 2,746,443

FUEL INJECTION PUMP Filed Feb. ,20, 1953 3 Sheets-Sheet 2 IN VEN TOR.WOLFGA N6 5 M5 YEP ATTOENEY United States 2,746,443 FUEL INJECTION PUMPWolfgang E. Meyer, State College, Pa., assignor to The Patent TexasCompany, New York, N. Y., a corporation of Delaware Application February20, 1953, Serial No. 338,043

3 Claims. (Cl. 123-139 The present invention relates to fuel injectionpumps for internal combustion engines and particularly to an improvedfuel-injection pump of the type wherein a single reciprocating androtating pumping plunger serves a plurality of engine cylinders.

in the operation of fuel injection pumps of the aforesaid itype withfuelpressure-actuated engine fuel injectors,

particularly when highly volatile fuels are used and when the pumpingfrequency is high, considerable difiicu'lty is commonly experienced inobtaining precise control of certain factors which are important tooptimum engine operation and efiicient combustion. Such factors astiming of the beginning and end of each fuel injection, and the quantityof fuel metered from the pump in 'each injcction, arepart-icularlydifiicult to control with precision, especially when thequantity of fuel delivered in each injection is small. This diflicultyis caused basically by thecompressibility of fuel in the fuel dischargepath from thepump to the engine fuel injector. 'When this fuel dischargepath has a relatively large volume in comparison with the volume of fueldischarged by the pump Mice 2 at a rate several times the engine speed,with very little time afforded between successive fuel discharges forrecondensation of any vaporized fuel inthe fueldischarge path. Hence, inpreventing vacuum formation in the fuel discharge path the deliveryvalve is particularly important.

However, use of the conventional delivery valve has the disadvantage.that the valve itself requires space in which @to be housed, which spacefurther adds to the compressible volume of the fuel discharge path andincreases its elasticity. Also, by immediately closing in response tothe reduction in pump output pressure which is intended to terminatefuel injection, the delivery valve blocks the fuel discharge path at itspump end and provides a reflecting surface for pressure waves in thedischarge path which usually accompany termination of fuel injection.The reflection of such pressure waves increases the likelihood ofsecondary or after-injections into the engine and thus-renders moredifiicult precise control of timing and duration of fuel injection.

The present invention provides a fuel injection pump of the type inwhich a single reciprocating and rotating plunger serves a plurality ofengine cylinders, and from which :the conventional delivery valve iscompletely elimi-.

. fuel discharge path fromthe pumping chamber of the for each injection,the compressibility of the fuel "tends to permit absorption of the fuelcharge from the pump into the fuel discharge path without anycorresponding displacement of 'fuel'through the fuel injector and 'intothe engine. This may result in actual fuel delivery to the engine ofonly aportion of the desired fuel charge. Also, -this elasticity of thesystem produces an unpredictable delay between the desired beginning.and ending I of fuel injection, as controlled by starting and stoppingof pumping 'in the fuel pump, and actual beginning and ending offuelinjectionat the injector.

One attempt to remedy this situation which is conventional in prior artfuel injection pumps is the, provision of a fuel pressure-operateddelivery valve which controls egress of fuel from the pumpand serves tomaintain fuel pressure 'in the fuel discharge path from pump toinjectorat a level close to .injection pressure during .theintervalbetween successive fuel discharges from the pump. This in effectmaintains the fuel in the discharge path in a precompressedstate andreduces its ability to absorb a fresh fuel charge delivered .by .thepump.

The fuel delivery valve also serves the .useful purpose .of isolatingthe fuel discharge path from thepump during the suction stroke of thepumping plunger. This prevents the rapid expansion of volume within thepumping chamber of the fuel pump from creating a vacuum in Because fuelvapor thus rupts the timing and accuracy of fuel metering. Thisdifficulty is aggravated during pump operation :at high engine speeds,and particularly so in the typeof fuel pump with which the presentinvention is concerned, wherein .a single pumping plunger serving fuelto .a plurality of engine cylinders must discharge successive fuelcharges pumpduring the suction stroke of the plunger, andthere- 'byprevents vacuum formation in the fuel discharge path, but .does notbring about such isolation until well after the termination of fuelinjection, so that any pressure waves accompanying injectiontermination, which might possibly be reflected in the discharge path,are effectively dissipated in .the fuel supply reservoir of the pump.This utilization of the rotating plunger as an effective deliverypermits .a considerable simplification, with attendant re- 45 ductioninvolume, of that portion of the fuel discharge path contained within-thefuel pump body. Thus, a fuel pump is provided from which the aforesaiddifficulties are substantially eliminated, and which is particularlysuited for precision control of fuel injection over a wide range ofoperating conditions.

An object of this invention therefore is to provide an improved fuelinjection pump for'use -with internal com- :bustion engines, in which asingle plunger is reciprocated and continuously rotated :for pumping andmetering the ,fuel and fordistr-ibuting it to more than one enginecylinder.

Another object is to provide a fuel injection pump of the aforesaid typein which the conventional fuel pressure-actuated delivery valve iseliminated.

Another .object is to provide a fuel injection pump of the aforesaidtype in which the path provided for the discharge of-fuel from'thepumping chamber to the engine is greatly simplified and substantiallyreduced in volume.

.ing fuel.

Another object is to provide a fuel pump of the aforesaid type in whichvacuum formation or fuel vaporization in the fuel discharge path duringthe suction stroke of the pumping plunger is prevented.

,Another object is to provide a fuel pump of the aforesaid type havingan improved degree .of precision of meter- Another object is to providea fuel pump of the aforesaid type, which is particularly suited formetering fuel to engines operating at relatively high speeds.

Another object is to provide a fuel injection pump of the aforesaid typein which vacuum formation in the pumping chamber during the suctionstroke of the pump plunger is eliminated.

Another object is to provide a fuel injection pump of the aforesaid typein which the beginning and the end of fuel injection can be variedindependently of each other.

Another object is to provide a fuel injection pump of the aforesaid typein which the entire fuel discharge path from the pump is maintained incontinuous fluid fuel contact with a low pressure fuel reservoir duringthe termination of fuel injection pressure in said discharge path, sothat pressure waves in said fuel discharge path arising from abrupttermination of fuel injection pressure are substantially damped out insaid reservoir without reflection, and secondary fuel injections arethereby eliminated.

Another object is to provide an improved fuel pump of the aforesaid typehaving a reduced number of parts of simplified design which can bemanufactured with greater ease and at reduced cost.

These and other objects and advantages of the invention will be apparentfrom the following description taken in connection with the accompanyingdrawings wherein:

Fig. 1 is a longitudinal sectional view of a pump constructed inaccordance with the present invention and showing the plunger in anintermediate portion of its stroke.

Fig. 2 is an enlarged view of a portion of Fig. 1.

Fig. 3 is an enlarged sectional view of the portion of the pump shown inFig. 2, taken on the line 3-3 of Fig. 2.

Fig. 4 is an enlarged sectional view of the portion of the pump shown inFig. 2, taken on the line 4-4 of Fig. 2.

Fig. 5 is an enlarged sectional view of the portion of the pump shown inFig. 2, taken on the line 55 of Fig. 2.

Fig. 6 is an enlarged cut-away perspective view of that portion of thepump shown in Fig. 2,. the portion cut away being defined by the line 66in Figs. 3 and 4.

Referring to the drawings, and particularly to Figs. 1 and 2, a singleplunger fuel injection pump constructed in accordance with the presentinvention is shown by way of example as adapted to serve a four-cylinderengine. The pump includes a housing 1 containing a body member 3provided with a cylindrical bore 5 which is enlarged adjacent one end toform a fuel sump 7. Slidably fitted within the bore 5 is a cylindricalpumping plunger 9 adapted for reciprocation and simultaneous rotationtherein in timed relation with the engine for which the pump suppliesfuel.

For reciprocating the plunger 9 within the bore 5 there is provided anengine-driven cam shaft 11 supported in housing 1 and carrying a cam 13which cooperates with a tappet roller 15 rotatably mounted in a tappet17. The tappet 17 is adapted to reciprocate within a bore 19 of housing1 in coaxial alignment with the bore 5 in the body member 3. One end ofplunger 9 is maintained in continuous contact with reciprocating tappet17 by means of compression springs 21 and 23 acting against a springretainer 25 supported from the end of the plunger by the usual splitcollar 27. At their other end springs 21 and 23 are restrained by aplunger rotation gear 31 which is keyed to plunger 9 intermediate itslength and which is adapted to bear against a surface 29 of the bodymember 3 while rotating.

To enable rotation of plunger 9 simultaneously with its reciprocation incylindrical bore 5, a pinion 33 connected in driving relation with gear31 is driven through a shaft 35 from a helical gear 37 mounted on camshaft 11.

At its end remote from sump 7, the bore 5 is permanently closed duringoperation of the pump, as by a plug 41. Plunger 9 forms with cylindricalbore 5 at this permanently closed end thereof a pumping chamber 43.During operation of the pump, fuel is admitted to pumping chamber 43 forcompression therein to the high pressures suitable for delivery to theconventional engine fuel injection equipment, and discharged therefromat a selected time in the engine cycle and in accurately metered amount.

In the case of thepump shown in the drawings, which is designed toprovide injection fuel to a four-cylinder engine, if the engine is ofthe four-stroke cycle type requiring two engine cylinder fuel injectionsfor each engine crankshaft revolution, then cam 13 and cam shaft 11 arearranged to reciprocate plunger 9 through two complete cycles,consisting of two compression and two suction strokes, during one enginecrankshaft revolution. Thus, if cam 13 is provided with two lobes, camshaft 11 should turn at engine speed for a four-stroke cycle fourcylinder engine. This could also be accomplished by providing cam 13with four lobes and turning cam shaft 11 at one half engine speed. Ifthe four-cylinder engine is of the two-stroke cycle type and cam shaft11 turns at engine speed, cam 13 should have four lobes. Also, in orderthat the pump may deliver its entire fuel discharge during a givenplunger compression stroke to but one engine cylinder, the ratio of theplunger rotating gear 31 and its driving pinion 33 should be such thatplunger 9 completes one full revolution during four-pumping strokes forfour-cylinder engine operation on either a two or four stroke cycle.That is, the plunger should rotate from the time it leaves its bottomdead center position on a compression stroke until it returns to bottomdead center after completing its suction stroke.

Body member 3 is provided with a plurality of fuel distributor ports 51,52, 53, 54 (only two of which are shown in Fig. 1), one for each enginecylinder, which communicate with the cylindrical bore 5 at pointspreferably equally spaced about a circumference in a crosssectionalplane thereof.

To each of the distributor ports 51, 52, 53, 54 is connected a fueldelivery line 55, 56, 57, 58 which conveys fuel to a particular enginecylinder fuel injection device. Distributor ports 51, 52, 53, 54 are solocated along cylindrical bore 5 as to be covered by plunger 9 duringthe whole of its reciprocating stroke. At its pumping chamber endplunger 9 is provided with a longitudinal fuel distributor slot 61 whichis of a sufficient length to intersect the plane of the distributorports during the entire reciprocating stroke of the plunger. By thisarrangement, any one of fuel distributor ports 51, 52, 53, 54 can bekept in fluid fuel contact with pumping chamber 43 during the entirelength of a plunger compression or suction stroke by proper rotativeorientation of plunger 9 to uncover the distributor port by distributorslot 61. Conversely, by so rotating plunger 9 that distributor slot 61does not uncover and come into fluid contact with any of the distributorports 51, 52, 53, 54, all of the distributor ports can be isolated frompumping chamber 43 during the whole of a plunger compression or suctionstroke. In the embodiment shown, slot 61 has a width in relation to thesize of ports 51, 52, etc., suflicient to uncover a distributor portduring substantially 45 of rotation of plunger 9.

Body member 3 is also provided with a plurality of fuel supply ports 71,72, 75, 76 communicating with cylindrical bore 5 at points along itslength between sump 7 and distributor ports 51, 52, 53, 54. These fuelsupply ports 71, 72, etc., are connected through a fuel supply passage45, in body member 3 to any desired source of low-pressure fuel, notshown. Sump 7 is also supplied with low pressure fuel through aconnection 49 in body member 3 to fuel supply passage 45. Together sump7 and the fuel supply passage 45 provide a low pressure fuel reservoirfrom which the pumping chamber 43 can be charged with fuel as the pumpoperates.

l plunger.

en arge -Fuel supply ports 71, 72, etc., are located .alo ngcylindricalbore 'sufficiently far from its closed end so that none of these portswill be uncovered by distributor slot 61 of plunger 9 during'any pointin the plunger suct'ion stroke, regardless of the rotative position ofthe Plunger 9 is provided also with a longitudinal fuel by-pass passage63 which opens into pumping chamber 43, and is of'sufiicient lengthwithin plunger 9 to extend into that portion of the plunger surroundedby fuel sump 7. At its fuel sump end the by-pass passage 63-is connectedto the fuel sump 7 through two longitudinally spaced upper and lowercontrol ports 81, 82 in plunger '9. Control ports 81 and 82 arepreferably aligned in the axial plane through'the plunger which bisectsthe distributor slot 61,'their longitudinal location and spacingpreferably being suchthat these ports will be confined Within fuel sump7 during the entire plunger excursion. Also provided within sump 7 are apair of control sleeves 91, 92 which surround the plunger 9 with a closesliding fit. Control sleeves 91, 92 are slotted to receive pins 101,162, respectively, which are eccentrically mountedion shafts 103, 104supported in body member 3 for rotation by suitable means external tothe pump, such ashand controls 105, 106, or any desired enginecondition-responsive device. By this arrangement, control sleeves 91, 92can be adjustably positioned along the plunger to cover the upper andlower control ports 81, 82, during any selected portion of the plungercompression stroke, and thereby prevent fuel flow between pumpingchamber 43 and fuel sump 7. Each control sleeve 9 1, 92 can bemanipulated independently of the other,

to cover and uncover the different control ports 81, 82 at differentpoints in the plunger excursion.

Inthe vicinity of fuel supply ports '71, 72, etc., plunger 9 isadditionally provided with two fuel fill ports '73, 74, connecting tothe longitudinal fuel by-pass passage 63. Fill ports 73, '74 aredisposed preferably on a common plunger diameter and inthe plunger axialplane of con- 1 trol ports 81, 82 and are so arranged as to uncover andcome into fluid fuel contact with fuel supply ports 71, 72, etc., duringcertain portions of the plunger suction stroke, as will be explainedmore fully hereinafter.

Operation of the pump will be described in terms of the sequence ofevents' taking place during one complete pressure fuel is .displaced'through distributor slot 61 n and the fuel discharge path consisting ofdistributor port '51 and'its connected fuel delivery line 55, to theappropriate fuel injection device onthe engine.

, tion of supply ports 71, 72, 75, 76 and distributor ports 51, 52,53,54, while slot 61 remains in contact with distributor port 51 fillports 73 74 are carried upward be tween adjacent supply ports withoutuncovering them.

As plunger 9 ascends further on its pumping stroke, lower control port82 emerges from lower control sleeve 92, thereby spilling high pressurefuel from pumping chamber 43 through longitudinal fuel ,by-pass passage63. This immediately terminates displacement of fuel at injectionpressure from pumping chamber 43. The abrupt drop in fuelpressure inpumping chamber 43, is

immediately communicated, through the still maintained fluidfuel'contactbetween chamber 43 and port 51, to the .pressure actuated engine fuelinjection device, and fuel injection ceases. However, since plunger slot61 remains in contact with port 51 during and after the termination ofinjection, the pressure waves which are plunger excursion, and withparticular reference to Fig. 6 V

- of the drawings, wherein is shown in enlarged schematic form theplunger 9, the ports .of bore 5, and control sleeves 91 and 92. Plunger9 begins its excursion from an initial position at bottom dead center,and with a rotative orientation at which one of the distributor ports,

rotation. At this point lower controlp ort $82 is normally covered bylower control sleeve 92, while upper control port81 is below the loweredge of upper control sleeve "91 and hence open to fuel sump '7. Alsoplunger fill ports 73, 74 are at this point below the vicinity of supplyports 71, 72, etc., and the rotative position of fill ports "'73, 74 istherefore not asyet important in determining compression stroke, asdetermined by the axial position of upper control sleeve 91, uppercontrol port 81*enters A upper control sleeve 91 and thereby closes olfpumping chamber '43 from fluid fuel contact with fuel sump 7. Thecompression :of plunger 9 builds fuehpressure up rapidly thereafter inpumping chamber and high-I n say 51, is just about to be uncovered byslot 61. This rotative orientation may, for reference, be termed 0 .of

usually present in the fuel dischargepath after theabrupt injectiontermination are allowed to travel back through the discharge path topumping chamber 43 and thence to fuel sump 7., wherein they areeffectively damped out without undesired reflection back to the engineinjection device.

Plunger .9 continues 'to rotate while ascending, and by the time itreaches top dead center position, it has rotated a sufiicient extent sothat fluid fuel contact has just .been broken between port 51 anddistributor slot 61.

Thus, when plunger 9 begins its downward or suction stroke under theinfluence of springs 21,23, and as permitted by .the rotation of cam13., distributor port "51 "is isolated from pumping chamber 43, and anytendency toward creationof a vacuum in the expanding volume of pumpingchamber 43 is not communicated through port 51.to the fuel dischargepath. The width of slot .61 in relation to the size of distributorports. 51 52, 53, and 54 is such that, during the entire angu 'larrotation of plunger 9 while on its suction stroke, slot 61 does not.uncover the next succeeding distributor ,port52, but .as plunger 9reaches bottom dead center the nearest edge of slot 61 is just about tobe rotated into uncovering relationship with distributor port .52. Thus,during the whole suction stroke of plunger 9'dis- .tributor slot 61 isrotatively positioned between adja- .cent distributor ports, whichthereby completely isolates all distributor ports 51, 52, .etc., frompumping chamber 43 during the plunger suction stroke.

As plunger 9 descends on the first portion .of its vsuction stroke,thefact that pumping chamber 43 .is .in communication with sump '7 through.by pass passage 63 and lower control port 82 prevents any vacuum.formation in pumping chamber 43. Later in the plunger descent, lowercontrol .port .82 reenters lower control sleeve 92. Since the order .ofevents .is reversed from the compression stroke, upper control .port 81has not as yet emerged from upper control sleeve 91. The .fluid fuelconnection between pumping chamber 43 and fuel sump ,7 is thereby.severed. This would .tend .to vcreate a vacuum in pumping chamber 43,but for the fact that the supply ports 71, 72, 75, 76 aresso positionedthat, at this plunger reciprocative and rotative ,position, at least onesupply port is uncovered by a plunger fill port 73, 574. Thus, fuel .isadmittedto pumping chamber 43 from .supply passage 45, and creation -ofa vac- 7 uum in chamber 43 is prevented. The disposition of supply ports71, 72, 75, 76 is thus determined by this requirement, namely that atleast one supply port must be uncovered by a plunger fill port at thetime when pumping chamber 43 becomes isolated from sump 7 during theplunger suction stroke. The supply and fill ports must also be of such asize as to maintain fluid fuel contact until further plunger descentpermits upper control port 81 to emerge from upper control sleeve 91.

As has heretofore been stated, plunger 9, is rotated continuously in onedirection and at constant speed by driving gear 31. As has also beenexplained, when serving a four-cylinder engine the plunger shouldcomplete one fourth of a full rotation, i. e., 90", during the period ofone complete reciprocating excursion. Since plunger 9 rotates atconstant speed, the proportion of its 90 rotation which accompanies itscompression stroke, relative to the proportion of its 90 rotation whichaccompanies its suction stroke, will be determined by the profile of thelobe of cam 13. If the cam lobe is symmetrical, for example, 45 ofplunger rotation will accompany its compression stroke and 45 willaccompany its suction stroke. If, however, it is desired that a largerproportion of the 90 rotation should accompany a plunger compressionstroke, then the plunger will be returned on its suction stroke during arelatively small fraction of the total excursion time, with acorrespondingly small amount of rotation. Thus, the shape of the camprofile is a factor which affects the disposition of fuel supply ports71, 72, 75, 76 relative to cylindrical bore 5. Provision as here shownof a plurality of supply ports, two of which are spaced 90 about acircumference of bore 5, and the other two of which are spaced somewhatless than 90 and in a cross-sectional plane displaced slightly from thefirst two, and provision of two diametrically opposite fill ports 73, 74in the plunger, permits a lengthened period of fluid contact betweensupply ports and fill ports during the plunger suction stroke withoutrequiring unusually large fill or supply ports. Of course it will beunderstood that the shape and size of the supply ports 71, 72, 75, 76,as well as fill ports 73, 74, may be varied as desired and as necessaryto maintain fluid contact therebetween during the period abovedescribed, and the relative size and shape of the ports shown in thedrawing is merely exemplary of one operative arrangement.

As the plunger 9 approaches bottom dead center, and upper control port81 emerges from the lower side of upper control sleeve 91 andreestablishes fluid contact between pumping chamber 43 and sump 7, theadditional plunger descent and plunger rotation carries fill ports 73,74 out of fluid contact with supply ports 71, 72, etc., and severs thisconnection between fuel source and"- pumping chamber 43. However,pumping chamber 43 remains connected to the low pressure fuel reservoirthrough upper control port 81 and sump 7 during the remainder of itssuction stroke until it reaches bottom dead center. Thus, it will beseen that during the entire plunger suction stroke, pumping chamber 43is at no time out of fluid fuel contact with a source of low pressurefuel, either through fill ports 73, 74 or'through upper or lower controlports 81, 82. This completely eliminates the possibility of fuelvaporization due to vacuum formation in pumping chamber 43.

Since the four distributor ports 51, 52, 53 and 54 are spaced equallyabout the circumference of bore 5, operation of the pump on subsequentplunger excursions, during which fuel is distributed through theremaining ports 52, 53, and 54, is identical with the pumping cycle forport 51 previously described, and hence need not be described.

Since the relative position of upper control port 81 and upper controlsleeve 91 at the start of the plunger compression stroke determines whatportion of the compression stroke will be completed before upper control'port 81 becomes enclosed Within upper control sleeve 91 and fueldisplacement from pumping chamber 43 begins, it will be appreciated thatraising the upper control sleeve 91 delays the start of fuel dischargefrom pumping chamber 43, and'lowering upper control sleeve 91 beginsfuel discharge earlier. Likewise, raising lower control sleeve 92 delaysuncovering of lower control port 82 and terminates fuel discharge fromchamber 43 later in the plunger'compression stroke, and lowering thelower control sleeve 92 terminates the fuel discharge earlier in theplunger compression stroke. Thus, varying the position of the twosleeves in unison varies the timing of fuel injection at the engine,relative to the engine crankshaft position.

Also, it should be recognized that since the two control sleeves 91 and92 can be moved independently, the distance between them may be varied.Thus, simultaneously raising upper control sleeve 91 and lowering lowercontrol sleeve 92 delays the beginning of fuel discharge from pumpingchamber 43, and also hastens its termination, thereby shortening theeffective pumping stroke of the plunger. Conversely, bringing the twocontrol sleeves 91 and 92 closer together lengthens the period in theplunger compression stroke during which fuel discharge takes place frompumping chamber 43. As an extreme example of this latter condition,upper and lower control sleeves 91 and 92 may be brought together untilthey are in contact and form one continuous enclosure about the controlports. In this case, there will be no by-pass connection through passage63 between pumping chamber 43 and fuel sump 7 during any portion of theplunger compression stroke. When the control sleeves 91 and 92 are inthis specialized position therefor, the plunger delivers fuel to a fueldelivery line during its entire compression stroke, thus effectivelyexpelling air from the pumping chamber 43 and the delivery line. Sincethe connection between the pumping chamber and the delivery line isbroken, when the plunger reaches its topmost position, and the deliveryline thereafter remains isolated until the plunger completes a fullrotation, fuel once pumped into this particular fuel delivery line hasno opportunity to return to the fuel sump. This arrangement thereforeprogressively expels air from the various delivery lines, and enableseffective priming of the pump.

Thus, there has been shown and described an internal combustion enginefuel injection pump from which the conventional delivery valve has beencompletely eliminated, enabling a substantial reduction in volume of thefuel delivery path between pump and engine without incurring vacuumformation and fuel vaporization in the discharge path or pumping chambereven during high speed operation and'with volatile fuels. Pumpsconstructed in accordance with the present invention are moreovercharacterized by greatly simplified internal fuel fiow passages as wellas provision for simple and effective control of the beginning andtermination of effective pumping, thereby providing a pump which is lessexpensive to manufacture, and which enables precision control of fuelinjection over a wide range of operating conditions.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims.

I claim:

1. In an internal combustion engine fuel injection pump of the typewherein a single plunger is employed for pumping and metering fuelanddistributing it to a plurality of engine cylinders, a body having a boretherein closed at one end and enlarged at the other end to form a fuelsump, a plunger adapted to reciprocate and rotate in said bore andforming at the .closed end of said bore a pumping chamber, means forreciprocating and simultaneously continuously rotating said plunger insaid bore, said fuel sump enclosini a portion of said plunger during thewhole of said reciprocation thereof, a fuel passage in said plungercommunicating with said pumping chamber, a plurality of control portmeans in said portion of said plunger enclosed within said fuel sumpconnected to said fuel passage and adapted to by-pass fuel from saidpumping chamber to said sump during a plunger compression stroke, afirst and a second movable means in said sump for isolating said controlport means from said sump during a selected portion of said plungercompression stroke respectively to produce injection fuel pressure insaid pumping chamber and to release said injection fuel pressure, aplurality of fuel distributing ports communicating with said bore atpoints equally spaced around a circumference of said plunger and locatedbetween said pump and said pumping chamber, a fuel distributing slot insaid plunger adapted to connect one of said fuel distributing ports tosaid pumping chamber during a plunger compression stroke and to isolatesaid distributing ports from said pumping chamber during a plungersuction stroke, fuel supply ports communicating with said bore andlocated between said fuel distributing ports and said fuel sump, andsupply ports in said plunger connected to said plunger passage andadapted to overlapsaid fuel supply ports to admit fuel to said pumpingchamber during the portion of said plunger suction stroke when saidplurality of control port means are otherwise isolated from said fuelsump.

2. A valveless fuel injection pump comprising, in combination, a lowpressure fuel reservoir, a high-pressure pumping chamber, a fueldelivery line, a pump plunger, means connecting said high-pressurepumping chamber to said fuel delivery line during the initial portion ofthe compression stroke of said plunger While at the same timemaintaining said high-pressure pumping chamber connected to said lowpressure fuel reservoir,

individual means on the continued compression stroke of said plungerfirst operatively disconnecting said low pressure fuel reservoir fromsaid high-pressure pumping chamber to initiate high-pressure fuel supplyto said delivery line, and then reconnecting said low pressure fuelreservoir with said high pressure pumping chamber to terminatehigh-pressure fuel supply to said delivery line respectively, said lastmentioned means then maintaining connection of said delivery line andhigh-pressure pumping chamber with said low pressure fuel reservoirduring the completion of said plunger compression stroke to damp outpressure waves in said system, means independently varying the timing ofthe initiation and termination of high-pressure fuel supply to saiddelivery line during the plunger compression stroke, and means duringthe entire succeeding plunger suction stroke disconnecting said fueldelivery line from said high-pressure pumping chamber while maintainingconnection of said high'pressure chamber with said low pressure fuelreservoir to prevent vacuum formation and vaporization of fuel in saidhigh-pressure pumping chamber.

3. A fuel injection pump according to claim 2, wherein the said pumpplunger simultaneously reciprocates and rotates to control high-pressurefuel supply in sequence to a plurality of fuel delivery lines, eachsupplied from said high-pressure pumping chamber.

References Cited in the file of this patent UNITED STATES PATENTS2,478,528 Edwards Aug. 9, 1949 2,544,561. Meyer Mar. 6, 1951 2,624,327Hogeman Jan. 6, 1953 2,640,419 Evans et a1. June 2, 1953 2,667,840 HighFeb. 2, 1954 FOREIGN PATENTS 359,603 Great Britain Oct. 29, 1931

